Such ski bindings, socalled midpoint ski bindings, have certain advantages compared with bindings having a jaw-heel system. Among others, the friction forces occurring during a horizontal release operation are substantially reduced, since the plate is arranged for movement about a ski-fixed axis of rotation and has to overcome a substantially smaller amount of friction than is the case with a ski shoe clamped between a heel holder and a front jaw and slides on the upper side of the ski. Furthermore, release moments which are independent of torque can be controlled with such bindings, since the distance from the front and rear clamping device to the center of rotation is the same in each case, whereby standardized shoe soles or plates on shoe soles are secured between the front and rear clamping device.
The release operation during a horizontal release is accomplished usually in such binding systems by a feeler mechanism measuring the amount of swivelling of the plate relative to the ski or the amount of torque which is created thereby, forwarding this information to the heel holder so that it releases beginning at a specific horizontal torque and releases the ski shoe upwardly when also a vertical moment occurs.
This type of release functions only as long as a vertical moment simultaneously exists. However, if due to a special type of fall a vertical moment does not exist, it can happen that the binding does not release the shoe in spite of a dangerous horizontal moment and thus does not preclude the danger of injury to the skier.
The purpose of the invention is now to provide a ski binding of the above-mentioned type, which upon an overload releases satisfactorily both vertically and also horizontally, whereby no vertical moments whatsoever must be needed to effect a horizontal release.
This purpose is attained by the invention for the first time by at least one of the two, preferably both, sole down-holding means being supported for pivotal movement in a transverse direction of the ski by means of bearings on a stepping plate which is hingedly connected to the heel holder and being fixed in their position holding the shoe in the skiing position by a locking member which can be released against the force of at least one spring and is engaged by a control part.
The invention makes it possible for the first time to release a ski binding vertically and horizontally with a plate which is rotatably supported about a ski-fixed axis of rotation, without requiring a vertical moment during the horizontal release.
The front clamping device can thereby be rigid or can have any desired form of conventional clamping devices.
For an optimum guiding of the shoe or the plate by the heel holder, it is provided inventively that the sole down-holding means have a gripping means mechanism, which grip, viewed in the longitudinal direction of the ski both laterally and also frontally at least at one point around corresponding points of engagement of the shoe or of a further plate on the shoe.
According to a development of the invention, each bearing is formed by an axle which is fixedly connected to the stepping plate, which makes it possible for the sole down-holding means to be able to follow the vertical elasticity of the heel binding.
The locking member is for the same reason also supported at least on one axis which is connected fixedly to the same stepping plate. The locking member is a bracket-shaped structural part.
According to a development of the invention, the ends of the bracket of the bracket-shaped structural part engage in their locked position of the sole down-holding means in correspondingly constructed receiving points thereon. It is preferable for the locking member to have an extent which is oriented substantially transversely with respect to the longitudinal direction of the ski and have at least one prong, so that the outer areas are formed by the bracket ends and the prong represents a point of engagement for the control part, and so that the prong can be disengaged from the control part during a vertical release by a lifting of the stepping plate. A structural part which is easy to manufacture is provided for the locking member in an advantageous manner by this development.
According to a further development of the invention, the control part is designed in two parts, the one part of which grips behind the prong by means of a hook and the other part of which engages a skifixed part. Each relative movement of the plate with respect to the ski thus results in a movement of the control part, which causes the locking member to be swung in a direction toward a release position. The control part can by itself also be divided in two at its side which projects from the locking member, so that both parts are constructed as projecting hooks and each engage a skifixed part. This special development of the invention assures in a simple manner a safe movement in both directions of rotation of the plate. The control part is thereby preferably supported in the plate and can thereby by all means be designed as a flat slide-member part.
A simplification in the construction results by fixedly arranging each skifixed part on a flangelike mounting on the vertically upright axis of the plate. For returning the control part it is provided that the hooks are biased by a further spring acting in the direction of the locking member to cause the sole down-holding parts to be locked again in a self-regenerating manner by swinging back following a release operation.
In order to fulfill the function of optimizing the separation between the heel-releasing mechanism and the horizontal-releasing mechanism it is furthermore provided that the prong projects downwardly and has a bent section against the direction of swing of the stepping plate, which bent section is designed preferably circularly, so that the midpoint of the radius lies at the centerline of the axis which supports the stepping plate.
The anchoring of the locking member is inventively assured simply and safely by the locking member having three prongs, whereby the prongs which flank the center prong also project downwardly and these two each receive a pivot pin which is supported in a downwardly projecting support arm on the stepping plate.
The self-regenerating of the sole down-holding parts is securely assured by a further development of the invention by urging these parts into the clamping position by the use of springs, preferably torsion springs.
In order to prevent a possible jamming of the locking device with the corresponding points of engagement in the sole down-holding means, according to a special development of the invention, it is provided that the sole down-holding means having sliding extensions which project toward the center of the ski and which are arranged at the height of the bracket ends and have a curvature having an approximately constant radius with respect to the swivel axis of the sole down-holding parts, the sliding extensions lie in one plane with the edge of the corresponding receiving points. The sliding extensions each preferably have a projection located at their ends remote from the sole down-holding means, which projections determine the extent of their pivoting movement, which is important after a horizontal release, since the projections prevent a possible damage to these parts, for example, by an excessive jamming thereof into the slope.
According to a further advantageous development of the invention, the stepping plate has a cam on its underside, which cam cooperates with a control cam, which through a slide member loads a third spring which influences the release force. The control cam is fixedly connected to a release lever for the voluntary release of the binding. The structural height of the heel holder is maintained low through this measure and furthermore a simple construction integration of the release mechanism of the heel binding into the plate or under the stepping plate of the heel binding is made possible.